Pump fluid pipe for an ejector pump and two methods for producing said pump fluid pipe

ABSTRACT

A fuel line ( 1 ) for a suction jet pump has a nozzle ( 2 ) which is produced integrally with a bend piece ( 3 ). This avoids shoulders, which may cause turbulence in a flow, within the fuel line ( 1 ). The suction jet pump equipped with this fuel line ( 1 ) is consequently particularly highly efficient.

[0001] The invention relates to a fuel line for a suction jet pump having a connection piece for connection of a connection line which leads onward, having a nozzle, which is intended to be mounted upstream of a mixer tube of the suction jet pump, and having a bend piece for connecting the connection piece to the nozzle. The invention also relates to an advantageous process for producing the fuel line from a plastic material, in which molten plastic is introduced into a mold provided for this purpose. Furthermore, the invention relates to a process for producing the fuel line from plastics, in which a blank which is in the form of a flexible tube is inflated in a mold.

[0002] Fuel lines of this type are often used to convey fuel within fuel tanks of modern motor vehicles and are known in practice. The connection line leads to a feed line to a fuel pump or to a return line, via which fuel is returned from an internal combustion engine of the motor vehicle to the fuel tank. The suction jet pump is used to feed fuel from one chamber of the fuel tank into another chamber or into a splash pot. The bend piece is in this case adapted for simple mounting of the connection line on the connection piece and is matched to the spatial conditions in the fuel tank. The bend piece is generally of undulating design or has a 90° or 180° bend. In the case of the fuel line which is known in practice, the end piece is produced as single component by welding together two half-shells which are produced by injection molding. The bend piece is then prestressed with respect to the nozzle.

[0003] A drawback of this arrangement is that considerable turbulence is imparted to a flow of fuel in the fuel line. As a result, the suction jet pump provided with the fuel line has a very low efficiency.

[0004] The invention is based on the problem of designing a fuel line of the type described in the introduction in such a way that flows of fuel in this line are guided with particularly low turbulence. Furthermore, it is intended to provide two processes, which are as simple and inexpensive as possible, for producing the fuel line.

[0005] According to the invention, the first problem is solved by the fact that the nozzle, the bend piece and the connection piece are produced integrally from plastics.

[0006] This configuration means that the fuel line according to the invention does not have any shoulders between the bend piece and the nozzle, and consequently no turbulence is imparted to the flow of fuel at this location. Therefore, as a result of the invention, fuel passes from the connection piece to the nozzle with low levels of flow losses. Consequently, the suction jet pump provided with the fuel line according to the invention is particularly highly efficient. Furthermore, swirling of the flow is reliably avoided in the region between the nozzle and the bend piece, which further increases the efficiency of the suction jet pump having the fuel line according to the invention.

[0007] A further contribution is made to reducing turbulence in the fuel line according to the invention if the inner side of the bend piece and of the nozzle is designed to be seamless.

[0008] A contribution is made to simplify mounting of the fuel line according to the invention if the bend piece and/or the nozzle are produced integrally with latching elements and holding elements which are intended for connection to adjoining components.

[0009] The second problem, namely that of providing a process which is as simple and inexpensive as possible for producing the fuel line from plastics is solved, according to the invention, by the fact that the cross section of the mold, at least at one end, is completely filled with the molten plastic, and that after the plastic at the wall of the mold has cooled, liquid plastic located in the core region of the mold is forced out by a high-pressure gaseous or liquid medium.

[0010] This process makes it possible to produce virtually any desired form of bends and cross-sectional changes in the fuel line. The invention means that it is not necessary to weld together shell parts of the fuel line, as in the known process. Consequently, the process entails a particularly small number of working steps and can therefore be used very economically in particular in series production, as is used for suction jet pumps for motor vehicles. A further advantage of this design is that the inner wall of the entire fuel line is formed by the flow of the medium and therefore does not have any seam. Consequently, turbulence in the flow of fuel within the fuel line produced using the process according to the invention is kept at a particularly low level. If there are high demands imposed on external dimensions of the fuel line, the mold may initially be completely filled with liquid plastic. In this way, moreover, it is also possible to produce holding elements and latching elements.

[0011] The final problem, namely that of providing a second simple and inexpensive process for producing the fuel line, is solved, according to the invention, by the fact that the blank is produced to have the same length as the fuel line and, before being inflated in the mold, is preshaped to match the fuel line outside the mold.

[0012] This process according to the invention makes it possible to ensure a uniform wall thickness of the fuel line. This leads to a particularly low use of material for the production of the fuel line. The fuel line produced using this process has a particularly smooth inner wall. Consequently, turbulence in the flow of fuel within the fuel line is kept at a particularly low level. In order for the blank to be preshaped, the latter can be heated in zones if necessary. Then, the preshaped blank can be deformed in the mold to form the fuel line.

[0013] The invention permits numerous embodiments. To further explain this basic principle, a plurality of these embodiments are illustrated in the drawing and are described below. In the drawing:

[0014]FIG. 1 shows a longitudinal section through a fuel line according to the invention,

[0015]FIG. 2 shows a liquid plastic which has been introduced into a mold for the fuel line before the core region is blown out,

[0016]FIG. 3 shows a blank of a mold which is in the form of a flexible tube, for a further embodiment of the fuel line.

[0017]FIG. 1 shows a fuel line 1 with a nozzle 2, a bend piece 3 and a connection piece 4 in longitudinal section, as well as components of a fuel tank 5, which are indicated by dot-dashed lines. The fuel line 1 is produced as a single part from plastics. Holding elements 6 and latching elements 7 are arranged on the outer side of the bend piece 3. Furthermore, dot-dashed lines in FIG. 1 show a mixer tube 8, which is directed onto the nozzle 2, of a suction jet pump arranged in the fuel tank 5. The suction jet pump is used, for example, to feed fuel from one chamber of the fuel tank 5 to a second chamber or into a splash pot. In the installed position of the suction jet pump, a line 9, which is likewise indicated by dot-dashed lines, is fitted onto the connection piece 4. The line 9 may, for example, be a branch from a feedline of a fuel pump.

[0018]FIG. 2 shows a mold 11, which has been filled with molten plastic 10, for a further embodiment of the fuel line during production of the latter. A pressure line 12 is connected to one end of the mold 11. During cooling of the plastic 10 in the mold, the edge region of the plastic solidifies first. This edge region forms the fuel line which is to be produced and is illustrated in dot-dashed lines in the drawing. At an intended thickness of the edge region, a gas is forced into the mold 11 at high pressure via the pressure line 12. This gas forces the plastic 10 which is still in liquid form in the core region out of the mold 11 at the other end. The fuel line can then be removed from the mold 11. This process allows the outer contour of the fuel line to be designed virtually as desired and provided with latching elements 13.

[0019]FIG. 3 shows a blank 14, which is in the form of a flexible tube, and half of a mold 15 for a further embodiment of the fuel line. The blank 14 extends over the entire length of the mold 15 and is preshaped in accordance with the fuel line which is to be produced. Moreover, the blank 14 is fitted onto a pressure line 16 and in a further operation can be inserted into the mold 15. Then, the blank 14 is inflated via the pressure line 16 until it bears uniformly against the inner wall of the mold 15. After the inflated blank 14 has been removed from the mold 15, its ends have to be processed further in order to complete the fuel line. 

1. A fuel line for a suction jet pump having a connection piece for connection of a connection line which leads onward, having a nozzle, which is intended to be mounted upstream of a mixer tube of the suction jet pump, and having a bend piece for connecting the connection piece to the nozzle, characterized in that the nozzle (2), the bend piece (3) and the connection piece (4) are produced integrally from plastics.
 2. The fuel line as claimed in claim 1, characterized in that the inner side of the bend piece (3) and of the nozzle (2) are designed to be seamless.
 3. The fuel line as claimed in claim 1 or 2, characterized in that the bend piece (3) and/or the nozzle (2) is produced integrally with latching elements (7, 13) and holding elements (6) which are intended for connection to adjoining components.
 4. A process for producing the fuel line as claimed in one of the preceding claims from a plastic material, in which molten plastic is introduced into a mold provided for this purpose, characterized in that the mold is completely filled with the molten plastic, and in that after the plastic at the wall of the mold has cooled, liquid plastic located in the core region of the mold is forced out by a high-pressure gaseous or liquid medium.
 5. A process for producing the fuel line as claimed in one of the preceding claims from a plastics material, in which a blank of the fuel line, which is in the form of a flexible tube, is inflated inside a mold, characterized in that the blank is produced to have the same length as the fuel line and, before being inflated in the mold, is preshaped to match the fuel line outside the mold. 